Why did she not read a book about becoming an adult instead?
She seems to be more mature, but she is still a kid. No one told her that there are more important things in life than partying; especially, with people who pay too much attention to it.
Halloween is not a problem; social media are not the problem either. Parents and teachers are failing our youngsters to tell from early childhood what essential things are in life, what is right and what is wrong. If that girl had that sense of rightfulness, she would feel compassionate about the pettiness of her colleagues, realizing that they do not deserve to be called friends.
Recently I wrote an article about Facebook, touching on this subject.